Daily, package delivery companies collect millions of packages from thousands of locations scattered over large geographical areas and transport them to sorting facilities for processing. After processing, the packages are carried to an equally large number of scattered destinations. To meet the rigorous schedules of today's business environment, while providing accurate deliveries of packages whose final destinations are literally everywhere in the world, sorting facilities are equipped with automated transfer systems whenever possible. These transfer systems must be fast, durable, easy to repair or replace, and provide gentle but accurate handling of each package.
Initially, laborers employed throughout the sorting facility comprised the sorting process; that is, they had to grab, lift, carry and place packages from one sorting station to another. Such use of labor produced an exceedingly slow and inefficient system that was plagued with human injury. While extensive use of labor has diminished as new and large sorting facilities are equipped with automated sorting and transfer systems, the sorting processes at old and small facilities often still rely on laborers at critical stations that require decisions regarding package placement. For example, at some old and small sorting facilities, conveyors typically feed packages to a cluster of laborers who must individually chose a package, pick it up, read the zip code or foreign address, then place the package on an output belt or into a chute associated with the packages' destination. This process is repeated in successively finer steps until the package is loaded onto a delivery vehicle assigned to a limited geographic area.
Those critical stations which are not automated remain burdened with the problems of manual labor and continue to be the source of delays and errors in an otherwise efficient process. Retrofitting these critical stations with automated devices is one solution taught by the automated sorting systems found in new facilities. For example, it is known to position a feed conveyor so that articles may be received from a single input source and transferred to a single output destination. In addition, it is known to adjust the feed conveyor so that articles may be transferred to additional output destinations. To accomplish the latter, an operator typically positions the feed conveyor between the input and desired output destination before loading articles onto the conveyor. However, such systems require an operator, are not readily adaptable to existing sorting systems, occupy a large amount of space, include complex mechanisms that are relatively difficult to repair, and are unable to move as fast as the existing automated transfer process.
U.S. Pat. No. 4,813,526 (Belanger) discloses a mobile conveyor unit that requires an operator to manipulate each change in destination; that is, swing laterally, raise or lower, and extend or retract the conveyor so articles can be transferred from one position to another. This transfer system is built with two conveyors and a large frame on a curved track that guides the sub-frame side to side while the transfer conveyor, pivoting about a horizontal axis at its entry end, moves up and down by means of hydraulic cylinders.
Similarly, U.S. Pat. No. 2,212,702 (Scott) describes a portable conveyor unit that requires an operator to position the frame then align the main conveyor by pivoting its entry end about a horizontal axis. The main conveyor extends from the horizontal axis, through a pair of upright posts, and terminates at an unsupported free end. The conveyor itself is raised and lower by cables and a winch, but has no provision for lateral movement once the frame is set in place. After the conveyor is positioned vertically, a safety rod is inserted through both the posts and conveyor to provide additional support for the conveyor while in its fixed position.
The transfer system disclosed in U.S. Pat. No. 5,090,549 (Thiel) is built of a series of conveyor sections which include a section that pivots about a horizontal axis for vertical movement and about a vertical axis for horizontal movement.
U.S. Pat. No. 1,753,036 (Williamson) discloses a manually powered letter sorter with a conveyor that can be raised or lowered and swung laterally between three positions in order to line up with a specific pigeonhole. The conveyor is aligned manually through the manipulation of levers and plungers.
While prior art teaches alignment of a feed conveyor between the input source and output destination, to achieve the desired alignment such devices require an operator to stop the apparatus, physically maneuver the feed conveyor as required, then restart the device before continuing the transfer process. Because each alignment requires shut-down, physical manipulation of the conveyor or conveyor controls, and start-up, these devices are incapable of rapid response to destination changes.
Portability, a strength in some prior art devices, is also a flaw when considering adoption into an existing process. For example, the drivable chassis of Belanger ('526) and bulky supporting structure of Scott ('702) prohibit integration within an enclosed structure of limited space. The Thiel ('549) apparatus, even if scaled down, is so large and complicated that it appears entirely restricted to outdoor use.
The primary thrust of the prior art devices, that include powered mechanisms for changing the orientation of a conveyor, is transferring as opposed to sorting articles. Such devices are capable of some degree of flexibility to provide alignment between input source and output destination, but are limited by lack of responsiveness. On the other hand, the manually operated Williamson ('036) device incorporates sorting capabilities but is limited by the cantilever conveyor design to very light and small articles, and is slow because it lacks automation.
Thus, existing transfer systems require an operator; are complex both mechanically and electrically; are by their nature large, bulky, slow and noisy; require significant maintenance; are not suitable for application in existing sorting facilities; and, where they do provide a means for sorting are slow and limited to very small and light articles. Accordingly, there has long existed a need in the art for a device that both transfers and sorts, does not require an operator, is simple in construction, requires little maintenance, is suitable for applicable in existing processes, provides a high throughput of sorted items per occupied floor space, and operates at a speed compatible with other automated devices in an automated process.